Question

How much work in joules must be done to stop a 920-kg car traveling at 90 km/h?

Answer 1

Work done, W = −287500 Joules

Step-by-step explanation:

It is given that,

Mass of the car, m = 920 kg

The car is travelling at a speed of, u = 90 km/h = 25 m/s

We need to find the amount of work must be done to stop this car. The final velocity of the car, v = 0

Work done is also defined as the change in kinetic energy of an object i.e.

`W=\Delta K`

`W=(1)/(2)m(v^2-u^2)`

`W=(1)/(2)* 920\ kg(0-(25\ m/s)^2)`

W = −287500 Joules

Negative sign shows the work done is done is opposite direction.